Finally tonight, our persons of the week. Three American heroes celebrated around the world, working together to save lives. Linsey Davis on one of the emotional homecomings. Reporter: A hero's welcome as the first of the three Americans praised for their quick, life-saving actions on that paris-bound train returns to U.S. Soil. Today, ABC's robin Roberts spoke exclusively with army national Guard specialist alek skarlatos. What was going through your mind when you first saw the guy on the train and the fact that he was armed? Well, I mean, I immediately recognized what was happening and I just thought there's just no way. Reporter: What happened landed the trio on the cover of "People" magazine. One week ago, what was supposed to be a european vacation for three childhood friends was upended by a man armed with an ak-47 appearing on their train. Alek hit me on the shoulder and said, let's go. Ran down and tackled him. Reporter: Alek skarlatos, along with his buddies Spencer stone and Anthony Sadler, becoming international icons, receiving France's highest medal. It was pretty much a gut reaction, just acting on adrenaline, doing what we had to do to survive. Reporter: Thanks to that gut reaction, an untold number of lives saved. And these three, now in the history books as heroes. Three heroes, our persons of the week.

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